Serging Savvy Series: Differential Feed

(the jacaranda trees are blooming now, to me the most visually arresting sight in queensland is the fleeting patches of purple that show themselves this time of year.  They glow valiantly, purple torches in the tired green treescape….  They’re in the header!)

Last week in the Tiramisu Circus, I bit off more than I could safely chew when I sat down to write about sergers/overlockers.  No matter how I tried, I couldn’t fit everything I wanted to cover in one post, so I broke it up into a series of posts.  This is the first of several “features” posts, to explore the functions of a serger/overlocker, discuss, and learn.

It’s up to you whether you want to use/shop for these features or not, I’m just here to chat about them!

Differential Feed?

Understanding and using differential feed helps create a quick, clean finish for any garment. (Not just knits!  Adjusting differential feed can help tame difficult wovens, too!)  It’s a feature of some overlockers/sergers, and has to do with the way the fabric feeds through the machine.

Note on names: Sergers and overlockers are different names for the same machines.  In America (where I learned to sew), we use the word “serger.”  In Australia (where I refined my skillz), we use the word “overlocker.”  Sorry if that caused any confusion!  What do you call this machine in your country/language?

Close Up Look

You saw this photo last week in The Circus, it’s a close up of my overlocker, which is fairly standard in many ways.

I have a Husqvarna 905, and she’s a workhorse.  (It’s a shame they discontinued the line, 905 and 910 are great machines.  Get one secondhand if you can.)  I removed the foot to allow a clear view of the feed dogs.  Many brands of overlockers feature “Differential Feed”- I think this is arguably the most useful feature of an overlocker.

Basically, “differential feed” means the machine has two sets of feed dogs- front and back.  The machine can be set so they work together at the same speed, or so they work at different speeds.  This allows for greater control and manipulation of the fabric.

My differential feed knob looks like this.  It’s located on the side of the machine, above the stitch length. N= “normal”- the default setting.  Right now, it is set to .5.

What does Differential Feed Do?

I used the same temperamental knit jersey from The Circus’ trials to illustrate differential feed.  In the top example, the differential feed was set lower than average.  This means the front feed dogs feed in the fabric slower than it is fed out of the machine, basically it’s the equivalent of stretching the seam as you sew.  In the second example, I left the differential feed at normal.  For the final sample, I turned the differential feed up.  I did not touch any other machine settings between samples.

Tip for sample sewing: adjust only one aspect of the stitching at a time, and do it gradually.

Here’s a close up- notice that the loops are a little “free.”  This is because the low differential feed setting stretches the fabric and it shrinks away from the blade.  If you want to create a rippled edge but also want tighter loops, you could try tightening the tension on the upper and lower loopers.  A little at a time, with plenty of testing.

Unrelated Tip:You can use this to create fluted edges.  Turn down the differential feed, gently tighten the looper tension and go for it.  Try this also on the “rolled hem” setting for a lettuce-leaf hem.

The second seam was stitched using the average setting for differential feed.  That means both sets of feed dogs work together at the same pace to feed the fabric through the machine.

When I sew with a new fabric, I usually test the various stitches I’ll use in the garment to be sure I like the settings.  I always start at “normal” or default settings and tweak from there.  This finish would normally be unacceptable to me, I’d know to turn up the differential feed to finish my seams.

Also, during the serging, I would see that the fabric cringes away from the blade.   Some woven linens do this, too, and turning up the differential feed helps eliminate this problem.

This is my differential feed turned up higher than average.  That means the fabric feeds in more quickly than it is let out; the back feed dogs “grip” the fabric so it slips and stretches less.  In fact, it’s the opposite of stretching the fabric.   LinB mentioned a manual equivalent of this when we were discussing prevention of rippled seams:

The differential feed functions essentially the same way as “crowding the fabric” at the back of the foot while sewing.  Neat!

I hope this helps clear up “differential feed”!  I wouldn’t be without it, and understanding the mechanics behind the feature absolutely leads to cleaner, neater sewing.

Do you ever use differential feed?  What do you call this machine where you’re from?  Do you have any tips for using differential feed to add to the discussion?

Up Next: Sourcing Eco-Knits

And then: Finished Object- Blue Seersucker Negroni

Next in the Serger Savvy Series: Presser Foot Pressure and Threading/Tension Options

By the way, I’m refraining from leaking Cake developments to the blog posts, all of that is now channeled into the Cake newsletter- sign up now so you don’t miss sneak peeks of the Tiramisu Dress instructions, as well as weekly sniplets about upcoming Cake releases.   Later on, this is also where I’ll introduce “hacks” and “mods” of my patterns.  I’ll also be hosting a few fun games and giveaways only open to Cake Updates subscribers.  Don’t miss out! It’s been slow up to now, but we’ll be cooking with gas very shortly.


  1. Oh I love the diff feed. Mostly my overlocker is set to roll stitch as I really only use it to roll hem chiffons and other light fabrics. I simply don’t like overlocking as a seam fiinsh, but I DO love it as a hem finish. The diff is so useful in setting the roll to ‘lettuce’ or not to ‘lettuce’ depending on the look I’m after :)

    • Yes- I go back and forth about overlocking as a seam finish… I do like HK seams (trousers) and French seams (blouses) and flat fell (shirts, trousers, jeans) but just can’t go past the overlocker for speed… ;) I think we mostly sew different stuff though…

      To Lettuce, or Not To Lettuce… ;)

    • Hi, I found this while trying to get help serging on a light weight satin/polyester prom dress. It has a serged hem as a finished from the factory, but I needed to cut off 4 inches. I thought it would be easy to just re-serge it, NOT SO MUCH!!!! I normally serge on cotton/poly blend with a wonderful neat finish. This is turning out terrible & I’m wondering if anyone here can help me with giving me tips? I have worked on the differential feed & adjusting the tension on the upper & lower loopers. Does anyone have any tips for doing this or any videos to watch on how to adjust for this type of fabric?

      • Hey-

        It’s really hard to tell what you might need to do without knowing your machine and seeing the fabric. Have you thought of trying a good old fashioned double roll hem? It’s more time consuming, but it’s a much cleaner finish. Baste a line 1/2″ or so from the raw edge. Press the hem to the wrong side along that edge. Baste in place. Fold again, press again, and then stitch with a regular stitch or a catch stitch or a blind hem stitch. That should make a nice edge, and it’s possible to do that even on a misbehaving fabric. Hope that helps, good luck!

  2. As I don’t have a walking foot of any type of differential feed on my sewing machine, it took me some time to discover this feature on my serger (we call it a surjeteuse in French, the other machine being a recouvreuse, not the same type of machine). I can’t wait for your post on sourcing eco-knits, because we only seem to have synthetic knits around here – even plain cotton jersey is hard to find!

    • Thanks for the French lesson! :) I would never have known.

      It’s weird, I keep hearing that about a lack of good knits in Europe. Perhaps one of our good indie online vendors in the region should take note…

      • They definitely should! I can understand why we don’t have a lot of merino knits, we don’t have many sheep in Europe anymore (though we’re able to find merino yarn to hand knit without much problem). But what I don’t get is the difficulty in finding cotton or even linen knits, especially as northern France is a big producer of linen. I never even knew there linen knits existed until I read your blog! Is linen knit available in RTW aswell in Australia?

        • I really don’t know what goes on in RTW here. I don’t even know the names of the shops. There’s a lot of talk about how Australian retailers are losing business to online competitors and I can certainly tell them why- cheap garbage-y merchandise badly curated in the shops combined with high prices and surly or inattentive retail staff who have never heard the term “Customer Service.” /end random rant

          I found some linen-cotton knit last summer and wore it all the time, to find it softened unbelievably with washing… Then I recently found some extremely lightweight linen jersey and made a wrap top. It’s delicious… I’m not sure where else to find it. I think I will be snapping it up whenever I see it…

          I’ll have a look around some online spots I know and let you know if I turn anything up. :)

        • I would love to get my mitts on some lovely merino knit. I love the one you used for the blank canvas tee hack.
          I also love these technical posts. I’m almost like a man in that I won’t read instruction manuals. Shocking I know.

          • Hmmmm… Every now and then I have the opportunity to get a good deal on merino… ;) And I have your mailing address! muahahahhahhaaaa

          • Ah! I finally found a place that sells merino online from New Zealand, but I haven’t ordered from them so I’m not solid on the quality etc. But it’s such an awesome fabric, it’s only a matter of time before you can get it locally… For an arm and a leg no doubt…

            • I hope so…and hope it’s not prohibitive. That said I’m off to London next month for a day that might include a bit of fabric shopping. ;-) Fingers crossed.

  3. No matter where I looked, I never understood this until you so clearly explained it! Thank you very much. I don’t own an overlocker, or “overlockmachine” it’s often called in The Netherlands, but am working my way towards it, financially, but especially mentally. :-)
    What I haven’t yet found is the explanation of the difference between an overlocker and a “cover stitch machine”. I figured it meant you don’t just have to do seams, but can sew things on top of the fabric. Can you find a way to tell us about that? The only thing I know is that it’s “extra” and you need to remove or change some bits of the machine.
    Would be grateful, but you’ve already solved mysteries and clarified the mumbojumbo. Thanks again!

    • Ah excellent. I worked out the details of it with my “industry” friend Janet, to be sure everything was correct. She has a very precise, exacting mind for these kinds of things… :)

      Yes- I think I can go play with the coverhem machine at a local shop, in exchange for a shout-out. I just need to go see. :) Definitely, definitely need to do an indepth coverhem post. Some overlockers do come with it as a function, but I find that in practice most people don’t like switching it over. A separate coverhem machine seems to be the way to go.

      • That would be great, thanks! Then I can think over what I’d like BEFORE a sales person gets to me :-). To add to your list – I’ve also heard “locker” and “lock(machine)” being used over here.

  4. Thank you – this was really useful! I’m a little nervous about my serger – so far, I’ve set it to the setting that works, and have refrained from playing with it at all. Which is silly – it won’t break. Off to try this tip!

    • Ah excellent! They can be a little intimidating at first, but the more you work on it and become comfortable, the more you’ll love it. :)

  5. It’s been absolute ages since I’ve used a serger (MO, US), and I don’t think my step-mom’s had differential feed, but then again, I was never very proficient.

    Now that I’m in New York, I hear serger and overlocker about equally. That might be because the only time I really hear about them is when the Viking Gallery ladies talk about them, or women who have bought them from there, so perhaps there’s a swing toward using the more European name because of branding?

    • That’s interesting that you hear them equally- very interesting! It might well be as you say. I love these kinds of details, thank you!

      • First time I ever used a serger was in the costume dept. at Southern Mississippi University. It was a monstrously huge industrial machine. They called it a merrow machine. Have since discovered that this is akin to calling a copier a “xerox,” a toothed slide fastener a “zipper,” a table tennis ball a “ping-pong” ball. Merrow was the company that developed the first commercially successful overlock machine, longer ago than you’d think: 1876. 1876! Good Lord.

  6. Ah interesting ~ I haven’t messed around with differential feed at all. I’ll have to check out my settings (they’re on the default) and experiment :)

  7. Thanks for the differential feed info. Unfortunately, my serger is a very old Brother that I inherited and it does not have differential feed. I will have to try Lin’s DYI method. At the moment, I ‘m just trying to get it to work. I changed the thread a couple of days ago and no matter how many times I re-thread it, it won’t stitch more than a few inches. I must have something wrong in the order of threading. Most frustrating.

    • Can you take a look at the manual? If you can find the model number you may be able to find a manual online. This will help you decide if you’re threading in the right order. USUALLY- usually- you thread the upper looper, lower looper, then the right needle and the left needle. This can vary though. I also have a little threading trick I’ll share next time that helps keeps the threads in place…

      Also double check that your tensions are set to normal and the presser foot is down. And I’d also just take out the needles and replace with ballpoints to err on the side of caution and then give it a whorl. Does it make a terrible sound at all? When was the last service? (Sorry! Not grilling you, just slipped into trouble shooting mode!)

  8. Hmm, I’ve never fiddled with my differential feed, but most of my seams look kind of wavy and gross. I’ll have to give this a try! This series has been so helpful– thanks a million!

    • Yeah no problem, I hope it works out for you! Just test test test on some scrap fabric, and adjust gently until you get the result you want.

  9. Thank you, I’ve heard of “differential feed” as important ever since I first started looking into overlockers (we call them sergers here in Canada, like the states, but I like overlocker better for some reason. Serger doesn’t sound like a real word.), but this is the first explanation that ever actually made sense to me! Yay. Now if only my serger had it…

    • No probs, Taran.. I use both words really without thinking about it. I speak a mongrel English! ;) I’m so pleased this made sense to you, very pleased. :)

      You can always borrow Linb’s trick. It works.

  10. Thanks for explaining! This is a feature I completely ignored up till now simply because I didn’t understand it. So helpful!
    We call the machine Overlocker in German – there is no extra German word for it (as far as I know).

    • Excellent! I’m so pleased to know you’ll be getting better use from your features! :)

      Cool- so it’s overlocker here, somtimes in NY, and in Germany.. Very interesting.

  11. Oh thank you I have an overlocker and I have used the differential feed with success but didn’t know exactly what it was doing to change things. I just got there by fiddling. I will be one super overlocker wiz thanks to you.

  12. Thank you again for a wonderful explanation – I have only had my serger for the last two years and am still trying to figure out all that it can do. My guess is that it does have the differential feed, since there is a dial that has glyphs like the one that you showed – now I will need to experiment.

    I was wondering if the lovely purple blossoms were jacaranda – we lived in Los Angeles when I was a child, and I remember how beautiful they were…

    • Oh yeah! Get in and experiment, it’s the best way to get to your know your individual machine. :)

      The Jacaranda bloomings are easily, easily the most beautiful thing about Brisbane. The color is almost violent, just brilliant and striking and gorgeous. Always gives me a lift to look at them. :)

  13. Ooh, I wonder if that’s what the knob under the cover for threading is.. (well that sentence is mildly unintelligible)

    As soon as I can think again I’ll go look at my instruction manual. Usually I ignore anything that isn’t the tension knobs, for fear of screwing something up.

      • Sorry, I broke my toe, and the combination of pain and drugs is making it hard to tell if I’m thinking clearly. Also I can’t sew because using the foot pedal hurts, but since I can’t think, that’s probably a good thing.

  14. You had me a Jacaranda! I grew up in Alaska where there typically aren’t any flowering trees. Every May in Los Angeles the streets just explode with purple trees!

  15. Pingback: Serging Savvy Series: Threading « 3 Hours Past the Edge of the World

  16. I have just been offered a serger 2nd hand but I know nothing about them. Will I ever get to know how to use it? It is a husq. 910 and I do have the manual but I think I need a dvd. It has a vcr but I don’t have the player. Can you please help me?

    • Hi Marg- The 910 is a really good model, solid and hard working. I’m happy to try to troubleshoot problems for you, but if you need lessons I’d suggest finding an independent Husqvarna dealer and find out if they run machine lessons. I’m not sure what I can do for you, is there a specific issue?

  17. Thanks so much for sharing the info on differential feed. I hate reading manuals! The explanations with pictures are first class.
    To create an extra wavy bottom on a shop-bought man’s merino V-neck sweater I transformed into a fitted one for me (10 euros in the sales so I felt free to experiment), I pulled on the fabric as I serged it. I had previously cut off all the rib. At the neckline, which I also cut to lower it, I added the cut off rib section as a trim after curling it on both long edges.
    By the way, my local fabric shop, Tissus Myrtille, in France, has patient, helpful and charming staff. (Just saying!) The UK, which I often visit and buy for my stash, is a joy for fabric, and for staff who are as obsessed with sewing and quilting as the customers. Cue: shop and talk for hours…
    Thanks again,

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